Supervised condition detection and alarm apparatus



ARATUS Sept. 25, 1962 J. w. MOBARRY SUPERVISED CONDITION DETECTION ANDALARM APP Filed Sept. 12. 1960 INVENTOR. JOHN w. MOBARRY BY ATTORNEYUnited States Patent ce 3 056 120 SUPERVISED CONDITIDN DETECTION ANDALARM APPARATUS John W. Mobarry, Edina, Minm, assignor to Minneapolis-This invention relates generally to electrical signaling systems andmore specifically to electrical alarm circuits which are responsive tothe occurrence of a dangerous condition to advise supervisory personnelof this condition. Apparatus of this general type may be used in fire,burglary, or any other application where it is desired to notifypersonnel in time for them to take precautionary measures.

In applications where human life is at stake, it is an absoluterequirement that the signaling system employed be highly reliable.Because of this reliability requirement, the systems disclosed in theprior art tend to be quite complex and expensive thereby pricing thissystem out of the reach of the average home owner. The alarm circuit ofthe present invention is relatively simple in form and quiteinexpensive. Notwithstanding these advantages, no sacrifice is made inthe reliability requirements deemed to be so necessary.

The alarm system of my invention is arranged to provide an audibleand/or visual indication upon occurrence of a dangerous condition towhich it is responsive. As mentioned above, this may, for example, be anover temperature produced by a fire, or any other occurrence where it isdesirable to notify supervisory personnel such that appropriate actionmay be taken. Additionally, provision is made in my alarm system to givean indication, either audible or visual, to supervisory personnel in theevent that a fault such as a short circuit or open circuit has occurredsomewhere in the system. Furthermore, there is provided in my system aself-contained auxiliary source of power which becomes operative tomaintain the system in a standby condition in the event of a powerfailure, and to cause the alarm to sound in the event that the dangerouscondition arises during the interval that the power has failed.

Included in my signaling system is a differential relay having switchmeans associated therewith. When the circuit is in its standbycondition, the switch means are in a first position in which both themain alarm and the fault indicator are inoperative. Upon the occurrenceof the dangerous condition, the balance condition of this relay isdisturbed so as to cause the switch means associated therewith to bemoved to a second or alarm position thereby allowing current to flowthrough said mainalarm causing it to operate. Furthermore, the circuitsare designed such that a fault occurring in the system is effective tocause an unbalance of the relay such that its associated switch means ismoved to still a third position in which the fault indicating alarm isenergized.

It is accordingly ,an object or" the present invention to provide animproved means for giving an alarm at a central location upon theactuation of distributed detector means, and also to provide meanswhereby a break or short circuit fault in the system may be signaled.

It is another object of my invention to provide an alarm system which isboth reliable and inexpensive.

Still another object of my invention is to provide an alarm system whichremains operative even when a failure of this main source of power hasoccurred.

Still other objects of the present invention will be hereinafter pointedout in the accompanying specification and claims and shown in thedrawing which by way of 3,056,120 Patented Sept- 25, 1962 2 illustrationshows the preferred embodiment of the invention.

Referring now to the schematic diagram shown in the drawing, there isillustrated a transformer 10 having a primary winding 12 and a secondarywinding 14. Primary winding 12 is adapted to be connected to aconvenient source of alternating current potential, such as a volt 60cycle source. Transformer 10* is effective to step down this voltage toa value suitable for use with the alarm. For example, the voltageappearing across terminals 16 and 18 of the secondary winding 14 may beapproximately 15 volts. Connected between the terminals 16 and 18, i.e.,directly across the secondary winding 14 is a power failure relay 20which operates a plurality of contact arms 20m, 20b, and 200. Theoperation of the power failure relay 20 will be described more fullyhereinbelow, but for now it is suflicient to say that in the event of apower failure the power failure relay and its associated contacts areoperative to switch an auxiliary source of power into the circuit and tosound a trouble alarm which will indicate this fault to the occupant ofthe premises where the apparatus is installed.

Continuing now with a description of the circuit layout, a conductor 22connects the secondary winding terminal 16 to a contact 24 of the powerfailure relay 20. A conductor 26 connects the switch arms 20a and 20b tothe junctions 28, 30, 32, and 36 and to the switch arm 38 of a singlepole double throw manual silencing switch 40. A conductor 42 is used toconnect the sec ondary winding terminal 18 to the junctions 44, 46 and48 and to the switch arms 50a, 50b, and 500 of an alarm relay 50.Connected between the junctions 28 and 32 on conductor 26 and thejunction 48 on conductor 42 is a balance circuit comprising a pair ofcurrent limiting resistors 52 and 54, the two coils 56 and 58 of abalanced relay, and a balancing potentiometer 60.

When normal line voltage is applied to the primary winding 12 oftransformer 10, the power failure relay 20 is energized therebycompleting a circuit path which may be traced through conductor 22,contact 24, switch arm 20a and conductor 26 to the junction 28. Atjunction 28, the current divides with approximately one-half of thetotal current flowing through the resistor 52, the balanced relay coil56 and a portion of the balancing potentiometer to the junction 48 andthe other half of the current flowing through a resistor 54, relay coil58 and the other portion of the balancing potentiometer to junction 48.At junction 48 the current again combines and flows through theconductor 42 back to the sec ondary winding terminal 18. 'Equality ofcurrent flow through the two coils of the balanced relay is obtained byinitially adjusting the position of the wiper arm 62 of the balancingpotentiometer 60.

The balanced relay coils 56 and 58 are arranged to operate a commonarmature 64. Armature 64 is shown as being rotatably mounted withrespect to a pivot or fulcrum 66. The armature 64 is provided with apair of contacts 68 and 70 located on opposite sides of the fulcrum 66.When the signaling circuit of this inven-' tion is in its standbycondition, i.e., the condition which exists when the system is free fromfaults and no dangerout condition is present, the armature 64 is in theposition illustrated. When the balance circuit becomes unbalanced dueeither to the occurrence of a dangerous condition or due to a systemfault the armature 64 is rotated either in the counterclockwisedirection or the clockwise direction about fulcrum 66 depending uponwhich of the balanced relay coils 56 M58 receives a greater portion ofthe current. Because a conductor 72 connects the armature 64 to thejunction 48 which, 'in turn, is connected by means of conductor 42 tothe secondary winding terminal 18, a counterclockwise rotation of thearmature 64 is effective to complete a circuit which may be traced fromthe secondary winding terminal 16 through conductor 22, contact 24,switch arm 2011, conductor 26, the alarm relay 50, and a contact 74which is arranged to mate with contact 68. In a similar manner, aclockwise rotation of the armature 64 about fulcrum 66 completes thecircuit between contact 70 and contact 76 so that a current can flowthrough the conductors 22, 26, the switch arm 38 of single pole doublethrow switch 40, a conductor 78, a fault indicating alarm 80, aconductor 82, through the armature 64 and the conductor 72, andconductor 42 back to the secondary winding terminal 18. The currentflowing through this last mentioned path is effective to energize thefault alarm 80.

Connected directly in parallel with the resistor 52 in the balancedcircuit is a main alarm 84. Connected directly in parallel with theresistor 54, i.e., between the conductors 86 and 88, are a plurality ofdetector means 90 and a termination or end of line resistor 92. Theconductors 86 and 88 pass through the areas of the premises to beprotected and one or more detector means 90 is provided for eachseparate area. Detectors 90 are illustrated as being of the normallyopen contact type which when exposed to a dangerous condition becomeclosed.

In order to supply energy to the circuit in the event of a failure ofthe line voltage, a battery source 94 is connected between the junction44 on conductor 42 and a contact 96 which cooperates with the powerfailure relay switch arm b. The potential appearing at the junction 32is normally applied through the conductor 26 and the single pole doublethrow manual silencing switch I to the fault alarm 80. When the switchis thrown from the position shown to its opposite position, a lamp 98 isinserted in the circuit between the junctions 36 and 44.

In completing the description of the circuit arrangement, a conductor100 connects the junction 46 on conductor 42 to the switch arm 200 ofthe power failure relay. Contact 102 which is associated with the switcharm 20c is connected by means of a conductor 104 to a junction 106 whichis the common point between the conductor 82 and a conductor 108.Conductor 108 connects the junction 106 to a contact 110 whichcooperates with the switch arm a of the alarm relay 50. A conductor 112is used to connect a contact 114, which is associated with the switcharm 50c, to one side of the main alarm 84. Also shown in the drawing isa conductor 116 which connects one side of the alarm relay 50 to thebalanced relay contact 74 and to a contact 118 which is associated withthe switch arm 50]) of the alarm relay.

Now that the circuit layout and various connections have been describedin some detail, a description of the circuit operation will bepresented.

Operation As mentioned earlier, the purpose of the signaling systemshown in the drawing is to sound an alarm whenever a condition arises towhich one or more of the detector means 90 is responsive, and to operatea fault indicator in the event that one or more of the circuitconnections which run throughout the building becomes either opened orshorted. When initially placed in operation, the circuit-is balanced byvarying the position of the wiper arm 62 of the potentiometer such thatthe magnetic force produced as a result of the current flowing throughthe balanced relay coil 56 is exactly counteracted by the magnetic forceproduced by the current flowing through the balanced relay coil 58. Whenthese forces are balanced, the armature 64 is in the position shown suchthat the switch means 68 and 70 is in its normal first or standbyposition, as illustrated. If the current flowing through the balancedrelay coil 56 decreases or the current Howing through the balanced relaycoil 58 increases from that which exists when the system is in balance,the armature members 64 will rotate counterclockwise about the fulcrum66 such that electrical continuity is established between the contacts68 and 74. When the armature 64 has been rotated in the counterclockwisedirection such that contacts 68 and 74 are closed and contacts 70 and 76are open, the circuit is said to be in its second or alarm position.Either an increase in the current flowing through the balanced relaycoil 56 or a decrease in the current flowing through the balanced relaycoil '58 causes the armature member 64 to rotate clockwise about thefulcrum 66 thereby causing contacts 70 and 76 to close and contacts 68and 74 to open. Under this condition, the switch means is said to be inits third or fault position.

When a source of line voltage is connected to the primary winding 12 oftransformer 10, a voltage is developed across secondary windingterminals 16 and 18 which is suflicient to energize the power failurerelay 20. Energization of relay 20 causes electrical continuity to beestablished between the switch arm 20a and contact 24 and breaks thecircuit between the switch arms 20b and 20c and their respectivecontacts 96 and 102. With electrical continuity established betweencontact 24 and switch arm 20a, a current path may be traced from thesecondary winding terminal 16 through conductor 22 through the nowclosed switch contact 24, the conductor 26, to the junctions 28 and 3 2.At junction 28 a portion of the current which normally flows in theconductor 26 divides and passes through the resistor 52 and the mainalarm 84 which is in parallel with resistor 52, through the balancedrelay coil 56, and through the balancing potentiometer wiper arm 62 tojunction 48. Likewise, at junction 32 a portion of the normal linecurrent flowing in conductor 26 divides so that a fraction of the totalcurrent flows through the resistor 54 and the balance relay coil 58 andthrough the portion of the balancing potentiometer 60 to the right ofthe wiper arm 62 to a junction 48. Also, a supervisory current flowsthrough the detector lines 86 and 88 and the end of line resistor 92. Inthe absence of a dangerous condition or system fault,

the wiper arm 62 of the balancing potentiometer 60 can be set such thatthe currents flowing through the balanced relay coils 56 and 58 aresubstantially equal thereby producing equal magnetic forces on thearmature 64 of the balanced relay. From junction 48 the current isreturned to the secondary winding terminal 18 by way of conductor 42.With the coils 56 and 58 exerting approximately equal forces on thearmature member 64, the circuit is in the standby condition and both thefault alarm and the main alarm 84 are silent. Should a dangerouscondition break out somewhere in the area being supervised, the normallyopen detector responds to this dangerous condition by closing itscontacts thereby shorting out the resistors 54 and 92. With theseresistors shorted out, there is an increase in the amount of currentwhich flows through the balanced relay coil 58 such that the coil 58produces a greater magnetic force on the armature 64 than does the coil56. As a result, the armature 64 is rotated in the counterclockwisedirection so as to establish electrical continuity between the contacts68 and 74. As mentioned previously, this is the alarm position for thebalanced relay armature. With contacts 68 :and 74 closed, a circuit pathmay be traced from the secondary winding terminal 16 through conductors22 and 26 to the junction 36. From junction 36 the current flows throughthe alarm relay coil 50 through the conductor 116 and the now closedcontacts 68 and 74, through the conductive armature 64 and the conductor72 to junction 48. The current which flows through the relay coil 50 isreturned from junction 48 to the secondary winding terminal 18 throughconductor 42. The current flowing through the relay coil 50 causes amagnetic force to be produced which causes the contact arms 50a, 50b and50c to close against their respective contacts 110, 118 and 114. Theclosure of the switch arm 5% against its associated contact 118 causesthe alarm relay coil 50 to be locked in itsenergized position. Theclosure of the switch arm 50c against its associated contact 114 iseffective to connect the main alarm 84 directly across the output of thesecondary winding 14 so that sufficient current can now flowtherethrough allowing it to sound. The closure of the alarm relaycontact 50a against its associated contact 110 establishes a currentpath from the junction 36, through conductor 26 and the single poledouble throw silencing switch 40, through conductor 78 and the faultalarm 80, through conductors 82 and 108 to the conductor 42 which isconnected to the secondary winding terminal 18. This current causes thefault alarm to sound. Once the occupant of the building hears the mainalarm he knows that a dangerous condition exists.

Since the lines 86 and 88 and the lines 87 and 89 connecting the mainalarm 84 to the control panel are strung throughout the building, mostbuilding codes require that these lines be supervised so that theoccupant will be advised of a break in these lines. Assuming that abreak does occur in either line 86 or 88, the end of line resistor 92would be disconnected so that it would no longer be in parallel with theresistor 54. The equivalent resistance in series with the balanced relaycoil 58 therefore increases. As a result, less current now flows throughthe balanced relay coil 58 so that the magnetic force produced by thiscoil is outweighed by the magnetic force produced by the balanced relaycoil 56. The armature member 64 therefore rotates in a clockwisedirection about the fulcrum 66 causing electrical continuity to beestablished between the contacts 70 and 76. Since the contacts 68 and 74are open when the armature 64 is in its third or fault position thealarm relay coil 50 remains deenergized. A current path may be traced,however, from the secondary winding terminal 16 through conductors 22and 26, through the silencing switch '40, through conductor 78 and thefault alarm 80, through conductor 82 and the now closed contacts 70 and76, through the armature 64 and conductor 72, back to the secondaryWinding terminal '18 by way of conductor 42. It can be seen, then, thatthe fault alarm 80 is, under these circumstances, connected directlyacross the secondary winding of the transformer 10. Sufficient currenttherefore flows through the fault alarm to cause it to sound. Shouldthesound from the fault alarm become objectionable to the occupant, once hehas been advised that a fault exists he may silence this alarm byreversing the position of the switch arm 38 of the manual silencingswitch 40 so as to connect the fault indicating lamp 98 directly acrossthe secondary winding 14.

In a similar manner, if a fault should occur in the form of a shortcircuiting of the main alarm 84 the amount of current flowing throughthe balanced relay coil 56 will exceed that flowing through the balancedrelay coil 58 again producing a clockwise rotation of the armature 64.As explained previously, this completes a circuit through the faultindicator 80' which will advise the occupant that a fault exists in thesystem so that he may take appropriate measures to correct thesituation.

Still another fault which may occur is that the lines connecting themain alarm into the circuit may become open. Under this condition, theeffective impedance in series with the balance relay coil 56 increasessuch that a greater magnetic force is applied to the armature 64 by thebalanced relay coil 58 than is applied by the balanced relay coil 56.Armature member 64 therefore rotates counterclockwise to close thecontacts 68 and 74. This is the same as the alarm condition previouslydescribed. As already mentioned, when contacts 68 and 74 close a currentflows through the alarm relay 50 by way of conductors 22, 26', 116, 72,and 42. With the alarm relay '50 energized its associated contacts 50a,

50b and 500 are pulled in. The closing of the'cont-act 50a against itsassociated contact 110 completes a circuit to connect the fault alarmdirectly across the output of the transformer 10. The closure of thecontact arm 50c across its associated contact 114 would cause the mainalarm 84 to ring, but since the fault which has been assumed is an openin the main alarm line, the main alarm 84 remains silent.

In the event of a power failure, no voltage will be induced in thesecondary winding 14 of the transformer 10 so that the power failurerelay 20 will become deenergized. With the power failure relay coil 20deenergized its associated contact arms 20a, 20b and 20c will assume theposition illustrated in the drawing. When contact arm 20b closes againstits associated contact 96 the auxiliary energy source 94- is connectedbetween the junction 44 and conductor 42 and the conductor 26. Currenttherefore can flow from the positive terminal of the source 94 throughthe conductor 26 to the junctions 28 and 32. As before, the currentdivides at these two points such that when no dangerous condition orfault (other than a power failure) exists, substantially equal currentswill flow through the balanced relay coils 56 and 58 and through eachhalf of the balancing potentiometer 60 and through conductor 42 back tothe negative terminal of source 94. The armature 64 of the balancedrelay therefore remains in its first or standby position. However, sincethe contact arm 200 of the power failure relay is now closed against itsassociated contact 102 a circuit path may be traced from the junction 32through conductor 26, through the single pole double throw manualsilencing switch 40, through the fault alarm 80 and conductors 82, 104,and 100. In effect, then, the fault alarm 80 is connected directlyacross the energy source 94 and therefore sounds.

Should a dangerous condition arise during the power failure, one of thenormally open condition responsive switches will close to short out thecurrent limiting resistor 54 and the'end of line resistor 92. Thecurrent flowing through the balanced relay coil 58 therefore increasesover the amount which normally flows and causes a counterclockwiserotation of the armature member 64. Current therefore flows from theauxiliary energy source 94 through the now closed contacts 96 andconductor 26 to the junction 36. From junction'36 the current continuesto flow through the alarm relay coil 50, conductor 116, the now closedcontacts 68 and 74, and conductors 72 and 42 back to junction 44 towhich the energy source 94 is connected. With the alarm relay coil 50energized, the relay contacts 50a, 50b and 500 associated therewithclose. When contact arm 50c closes against its associated contact 114the main alarm 84 is connected directly across the energy source 94 sothat it is able to sound.

Thus it can be seen that this circuit of this invention is effective togive an alarm to indicate the presence of a dangerous condition to whichthe detectors 90 are responsive, and to provide an indication tosupervisory personnel in the event that a fault occurs in the system.

From the above description it will be apparent that I have produced asystem apparatus which possesses all of the features that are set forthas desirable; and while I have described and illustrated what appears tobe the preferred form of the invention, I reserve the right to make allchanges within the spirit of the invention and without the ambit of theprior art.

I claim:

1. In a supervised condition detection and alarm apparatus, first alarmmeans for indicating the presence of an undesired condition, secondalarm means for indicating the presence of circuit trouble, switchactuating means having a balanceable member normally held in a centerposition and controlled by a first and a second winding to close a firstswitch when said member moves in a first direction and to close a secondswitch when said member moves in an opposite direction, said firstswitch being closed when an output of said first winding produces todominating force on said member, said second switch being closed when anoutput of said second winding produces the dominating force on saidmember, a source of power, a plurality of abnormal condition detectormeans, said detector means being normally open and connected inparallel, an end impedance connected adjacent a farthermost of saidparallel detector means, a first resistance connected adjacent a closestof said detector means, circuit means including said first switch forconnecting said second alarm to said source, circuit means includingsaid second switch for connecting said first alarm to said source,circuit means including a parallel circuit of said first resistance,said end resistance and said parallel detectors for connecting saidsecond winding to said source, a second resistance connected in parallelwith said first alarm means, and circuit means comprising said secondresistance for connecting said first winding to said source.

2, In a supervised condition detection and alarm apparatus, first alarmmeans for indicating the presence of an undesired condition, secondalarm means for indicating the presence of an abnormal circuit, a sourceof power, switch actuating means having a balanceable member controlledby a first and a second Winding to close a first switch when said membermoves in a first direction and to close a second switch when said membermoves in an opposite direction, said first switch being closed toencrgize said second alarm means when said first winding produces todominating force on said member, said second switch being closed toenergize said first alarm means when said second winding produces thedominating force on said member, a plurality of parallel connectedabnormal condition detector means, said detectors closing upon thepresence of an undesired condition, an end resistance connected adjacenta farthermost parallel detector means, a first resistance connectedadjacent a closest detector means, circuit means including a parallelcircuit of said first resistance, said end resistance and said paralleldetectors for connecting said second winding to said source, a secondresistance connected in parallel with said first alarm means, andcircuit means comprising said second resistance for connecting saidfirst winding to said source.

3. In a supervised condition detection and alarm apparatus, first alarmmeans for indicating the presence of an abnormal condition, second alarmmeans for indicating the presence of an abnormal circuit, switchactuating means having a pivoted member controlled by a first and asecond winding to close a first switch when said member moves in a firstdirection and to close a second switch when said member moves in anopposite direction, said first switch being closed when said firstwinding produces to dominating force on said member, said second switchbeing closed when said second winding produces the dominating force onsaid member, circuit means for adjusting the resultant etfect of theoutput of said windings on said member, a source of power, at least onenormally open circuit abnormal condition detector means, a circuittermination means connected in parallel with detector means at one endof a circuit, a first resistance connected in parallel with detectormeans, circuit means including said first switch for connecting saidsecond alarm to said source, circuit mean including said second switchfor connecting said first alarm to said source, circuit means comprisingtwo parallel conductors connecting said first resistance, saidtermination means and said detector in parallel for connecting saidsecond winding to said source, a second resistance connected in parallelwith said first alarm means, and circuit means comprising said secondresistance for connecting said first winding to said source.

4. In a supervised condition detection and alarm apparatus, first alarmmeans for indicating the presence of an undesired condition, secondalarm means for indicating the presence of circuit trouble, switchactuating means having a balanceable member controlled by an output of afirst and a second actuator Winding to close a first switch when saidmember moves in a first direction and to close a second switch when saidmember moves in an opposite direction, said first switch being closedwhen said output of said first winding produces to dominating force onsaid member, said second switch being closed when said output of saidsecond Winding produces the dominating force on said member, a source ofpower, a plurality abnormal condition detector means, said detectormeans being normally open and connected in parallel, an end resistanceconnected adjacent a farthermost of said parallel detector means, afirst resistance connected adjacent a closest of said detector means,circuit means including said first switch for connecting said secondalarm to said source, circuit means including said second switch forconnecting said first alarm to said source, voltage balancing circuitmeans, circuit means including a parallel circuit of said firstresistance, said end resistance, said parallel detectors and saidvoltage balancing circuit means for connecting said second winding tosaid source, a second resistance connected in parallel with said firstalarm means, and circuit means comprising said second resistance forconnecting said first winding to said source.

References Cited in the file of this patent UNITED STATES PATENTS2,074,262 Grant Mar. 16, 1937 2,728,904 Schafer Dec. 27, 1955 2,891,240Rohulich June 16, 1959

